Polish Polar Research

Eocene penguin remains from Seymour Island (Antarctica) are so far the oldest−known record of extinct Sphenisciformes. Rich Argentineand Polish collections of penguin bones from the La Meseta Formation are taxonomically revised on tarsometatarsal morphology. Two genera and four species are erected: Mesetaornis polarisgen. et sp. n., Marambiornis exilisgen. et sp. n., Delphinornis arctowskiisp. n. and D. gracilissp. n. Moreover, the diagnoses of already described species: Anthropornis nordenskjoeldi, A. grandis, Palaeeudyptes klekowskii, P. gunnari, Archaeospheniscus wimani and Delphinornis larseniare revised as well. Gradual cooling of climate, changes of environment andtrophic relationships, that lasted several millions years, were most probably responsible forthe intense speciation and taxonomic diversification of the Middle–Late Eocene La Meseta penguins.

Cockburn Island is one of the most historically significant places on the Antarctic continent. The isle was first surveyed in early 1843 during Captain James Ross’ famous expedition, but the early explorers failed to recognise its geological and palaeontological significance. Cockburn Island is exceptional for it has the only succession of Upper Cretaceous, Eocene and Miocene–Pliocene rocks on the continent, which is now known to contain an admirable and diverse fossil record of fauna and flora. These fossil assemblages are providing exciting new information on the evolutionary history of Antarctica. At least 22 species of Late Cretaceous macroinvertebrates and vertebrates have been recognised, whereas the Eocene record is slightly more diverse at 28 macroinvertebrate taxa recorded. The Pliocene macrofossil record is depauperate atsome 11 species, butmicrofossils (diatoms, ostracods, foraminifera) are represented by at least 94 taxa. The palaeoecologic and palaeobiogeographic significance of fossil assemblages is explored in this paper. Further, a checklist of fossils is presented herein, for the first time, as is a bibliography of the geology and palaeontology of the island.

Brachiopods are reported for the first time from the Lower Miocene Cape Melville Formation of King George Island, South Shetland Islands, West Antarctica. Two genera, Liothyrella Thomson and Paraldingia Richardson have been identified. This is the first occurrence of Paraldingia in Antarctica.

The Marhřgda Bed occurring at base of the Adventdalen Group in Sassenfjorden, Spitsbergen contains common ankerite–replaced belemnite skeletons. Petrographic, major element geochemical, and stable carbon and oxygen isotopic data indicate that the ankerite originated in a catagenic environment associated with thermal degradation of kerogenan d hydrocarbongen erationinthe sequence. It formed at maximum temperature of 150°C under burial of approx. 2 000 m, most probably during Paleogene filling and subsidence of the Central Spitsbergen Basin. Dissolution of biogenic calcite and precipitation of ankerite reflect extensive heat flow through the Adventdalen Group sequence related to the Cretaceous and Paleogene magmatic and orogenic activity in Svalbard.